Physically motivated X-ray obscurer models

Year: 2021

DOI: 10.1051/0004-6361/201834963

Context. The nuclear obscurer of active galactic nuclei (AGN) is poorly understood in terms of its origin, geometry, and dynamics.

Aims. We investigate whether physically motivated geometries emerging from hydro-radiative simulations can be differentiated with X-ray reflection spectroscopy.

Methods. For two new geometries, the radiative fountain model and a warped disk, we release spectral models produced with the ray tracing code XARS. We contrast these models with spectra of three nearby AGN taken by NuSTAR and Swift/BAT.

Results. Along heavily obscured sightlines, the models present different 4−20 keV continuum spectra. These can be differentiated by current observations. Spectral fits of the Circinus Galaxy favour the warped disk model over the radiative fountain, and clumpy or smooth torus models.
Conclusions. The necessary reflector (N_H ≥ 10²⁵ cm²) suggests a hidden population of heavily Compton-thick AGN amongst local galaxies. X-ray reflection spectroscopy is a promising pathway to understand the nuclear obscurer in AGN.